1. Field of the Invention
The invention relates to a picture display device including a generator circuit for generating a periodical waveform for addressing picture elements on a picture display screen, said circuit comprising a time-determining network including a capacitor.
Recently, advanced techniques have made it possible to integrate time-determining RC networks in a semiconductor body. This integration requires very strict tolerances of the order of 1 to 2% in order to preclude adjustments. However, when integrating these networks, the tolerance is of the order of 5 to 10% for the capacitors and 10 to 15% for the resistors, and moreover, the resistors have a noticeable temperature coefficient.
2. Description of the Related Art
A circuit in a picture display device for generating periodical waveforms for addressing picture elements on a picture display screen, for example, the deflection in a picture display tube, comprises inter alia generators, for example, sawtooth generators or controllable oscillators which are synchronized with line and field frequency signals, respectively, present in an incoming video signal. The integrated circuit of the Philips type TDA 8370 is an example of such a circuit. If the time-determining elements of the generators are also to be integrated in the same semiconductor body comprising the greater part of the circuit, the tolerances may lead to inadmissible variations in the nominal frequency and in the nominal amplitude of the waveforms generated by the generators.